Question

(79)³ with formula and steps​

Answer 1

Answer:

That is the answer

I hope it's Help

Answer 2

$\overline{\underline{\boxed{\sf GIVEN \darr}}}$

(79)³ without actual multiplication

$\overline{\underline{\boxed{\sf SOLUTION \darr}}}$

79 can be written as 80 - 1 which equals 79

So,

(79)³ = (80 - 1)³

Let us assume :

80 be a

1 be b

Now it can be written as :

(a - b)³

Applying identity to get (a - b)³ : (a - b)³ = a³ - b³ - 3ab(a - b)

• a³ - b³ - 3ab(a - b)

Putting the values we get

• (80)³ - (1)³ - 3 × 80 × 1(80 - 1)

Simplifying it we get

• 512000 - 1 - 240 × 79

• 512000 - 1 - 18960

• 512000 - 18961

• 493039

So, the cube of 79 is 493039

$\overline{\underline{\boxed{\sf KNOW \: MORE \darr}}}$

• ( a + b)² = a² + b² + 2ab

• ( a - b )² = a² + b² - 2ab

• ( a + b )² + ( a - b)² = 2a² + 2b²

• ( a + b )² - ( a - b)² = 4ab

• ( a + b + c )² = a² + b² + c² + 2ab + 2bc + 2ca

• a² + b² = ( a + b)² - 2ab

• (a + b )³ = a³ + b³ + 3ab ( a + b)

• ( a - b)³ = a³ - b³ - 3ab ( a - b)

• If a + b + c = 0 then a³ + b³ + c³ = 3abc